1. Field
This disclosure relates to wireless energy transfer and tuning of resonators to accomplish such transfer.
2. Description of the Related Art
Energy or power may be transferred wirelessly using a variety of known radiative, or far-field, and non-radiative, or near-field, techniques as detailed, for example, in commonly owned U.S. patent application Ser. No. 12/613,686 published on May 6, 2010 as US 2010/010909445 and entitled “Wireless Energy Transfer Systems,” U.S. patent application Ser. No. 12/860,375 published on Dec. 9, 2010 as 2010/0308939 and entitled “Integrated Resonator-Shield Structures,” U.S. patent application Ser. No. 13/222,915 published on Mar. 15, 2012 as 2012/0062345 and entitled “Low Resistance Electrical Conductor,” U.S. patent application Ser. No. 13/283,811 published on Oct. 4, 2012 as 2012/0248981 and entitled “Multi-Resonator Wireless Energy Transfer for Lighting,” the contents of which are incorporated by reference.
Magnetic resonators may need to be tuned to achieve desired and/or specified performance metrics. To achieve the desired or specified performance metrics for wireless energy transfer, resonators' parameters may need to be within a specific range. For example, in some embodiments a resonator resonant frequency may need to be within a range of the system resonant frequency for example. In other embodiments the resonator may need to be impedance matched to an amplifier, rectifier or other circuitry.
Components used to build and assemble magnetic resonators and power and control circuitry may be specified within a range of tolerances or variability in their component values. Components such as capacitors, inductors, circuit boards, oscillators, resonator coils, transistors, diodes, switches, and the like, may have a rated and/or specified nominal value, but may actually have a value different than the nominal value. In some embodiments for example, variations in the inductance of a resonator coil, or variations in the capacitance of capacitors may result in actual resonant frequencies that are different than the intended and/or designed resonant frequency of the resonator. In other embodiments, variations in inductance of the coil or variations in the capacitance of capacitors may affect the impedance matching between amplifiers, rectifiers, resonators, or any of the circuits. In some embodiments of resonators, the parameters of the resonators may be perturbed by objects in the environment around the resonators.
There are thus many ways in which the frequency and/or the impedance matching of the resonator may be outside of the desired or optimum range due to environmental, manufacturing, operating, and the like, uncertainties. What is needed is a simple and way to tune the resonator parameters to compensate for environment perturbations, manufacturing uncertainty, component variability, and the like.